2 '\" Copyright (c) 2001 by Kevin B. Kenny <kennykb@acm.org>.
4 '\" See the file "license.terms" for information on usage and redistribution
5 '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
7 .TH Tcl_GetTime 3 8.4 Tcl "Tcl Library Procedures"
8 .\" The -*- nroff -*- definitions below are for supplemental macros used
9 .\" in Tcl/Tk manual entries.
11 .\" .AP type name in/out ?indent?
12 .\" Start paragraph describing an argument to a library procedure.
13 .\" type is type of argument (int, etc.), in/out is either "in", "out",
14 .\" or "in/out" to describe whether procedure reads or modifies arg,
15 .\" and indent is equivalent to second arg of .IP (shouldn't ever be
16 .\" needed; use .AS below instead)
19 .\" Give maximum sizes of arguments for setting tab stops. Type and
20 .\" name are examples of largest possible arguments that will be passed
21 .\" to .AP later. If args are omitted, default tab stops are used.
24 .\" Start box enclosure. From here until next .BE, everything will be
25 .\" enclosed in one large box.
28 .\" End of box enclosure.
31 .\" Begin code excerpt.
36 .\" .VS ?version? ?br?
37 .\" Begin vertical sidebar, for use in marking newly-changed parts
38 .\" of man pages. The first argument is ignored and used for recording
39 .\" the version when the .VS was added, so that the sidebars can be
40 .\" found and removed when they reach a certain age. If another argument
41 .\" is present, then a line break is forced before starting the sidebar.
44 .\" End of vertical sidebar.
47 .\" Begin an indented unfilled display.
50 .\" End of indented unfilled display.
53 .\" Start of list of standard options for a Tk widget. The manpage
54 .\" argument defines where to look up the standard options; if
55 .\" omitted, defaults to "options". The options follow on successive
56 .\" lines, in three columns separated by tabs.
59 .\" End of list of standard options for a Tk widget.
61 .\" .OP cmdName dbName dbClass
62 .\" Start of description of a specific option. cmdName gives the
63 .\" option's name as specified in the class command, dbName gives
64 .\" the option's name in the option database, and dbClass gives
65 .\" the option's class in the option database.
68 .\" Print arg1 underlined, then print arg2 normally.
71 .\" Print arg1 in quotes, then arg2 normally (for trailing punctuation).
74 .\" Print an open parenthesis, arg1 in quotes, then arg2 normally
75 .\" (for trailing punctuation) and then a closing parenthesis.
77 .\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
81 .\" # Start an argument description
85 . ie !"\\$2"" .TP \\n()Cu
90 \&\\$1 \\fI\\$2\\fP (\\$3)
103 .\" # define tabbing values for .AP
106 .if !"\\$1"" .nr )A \\w'\\$1'u+3n
109 .if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n
110 .nr )C \\n()Bu+\\w'(in/out)'u+2n
112 .AS Tcl_Interp Tcl_CreateInterp in/out
113 .\" # BS - start boxed text
114 .\" # ^y = starting y location
122 .if n \l'\\n(.lu\(ul'
125 .\" # BE - end boxed text (draw box now)
130 .ie n \l'\\n(^lu\(ul'
132 .\" Draw four-sided box normally, but don't draw top of
133 .\" box if the box started on an earlier page.
135 \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
138 \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
145 .\" # VS - start vertical sidebar
146 .\" # ^Y = starting y location
147 .\" # ^v = 1 (for troff; for nroff this doesn't matter)
151 .ie n 'mc \s12\(br\s0
154 .\" # VE - end of vertical sidebar
162 \h'|\\n(^lu+3n'\L'|\\n(^Yu-1v\(bv'\v'\\n(^tu+1v-\\n(^Yu'\h'-|\\n(^lu+3n'
169 .\" # Special macro to handle page bottom: finish off current
170 .\" # box/sidebar if in box/sidebar mode, then invoked standard
171 .\" # page bottom macro.
178 .\" Draw three-sided box if this is the box's first page,
179 .\" draw two sides but no top otherwise.
180 .ie !\\n(^b-1 \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
181 .el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
184 .nr ^x \\n(^tu+1v-\\n(^Yu
185 \kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c
198 .\" # DS - begin display
204 .\" # DE - end display
210 .\" # SO - start of list of standard options
212 'ie '\\$1'' .ds So \\fBoptions\\fR
213 'el .ds So \\fB\\$1\\fR
214 .SH "STANDARD OPTIONS"
220 .\" # SE - end of list of standard options
225 See the \\*(So manual entry for details on the standard options.
227 .\" # OP - start of full description for a single option
232 Command-Line Name: \\fB\\$1\\fR
233 Database Name: \\fB\\$2\\fR
234 Database Class: \\fB\\$3\\fR
238 .\" # CS - begin code excerpt
244 .\" # CE - end code excerpt
249 .\" # UL - underline word
253 .\" # QW - apply quotation marks to word
255 .ie '\\*(lq'"' ``\\$1''\\$2
256 .\"" fix emacs highlighting
257 .el \\*(lq\\$1\\*(rq\\$2
259 .\" # PQ - apply parens and quotation marks to word
261 .ie '\\*(lq'"' (``\\$1''\\$2)\\$3
262 .\"" fix emacs highlighting
263 .el (\\*(lq\\$1\\*(rq\\$2)\\$3
265 .\" # QR - quoted range
267 .ie '\\*(lq'"' ``\\$1''\\-``\\$2''\\$3
268 .\"" fix emacs highlighting
269 .el \\*(lq\\$1\\*(rq\\-\\*(lq\\$2\\*(rq\\$3
271 .\" # MT - "empty" string
277 Tcl_GetTime, Tcl_SetTimeProc, Tcl_QueryTimeProc \- get date and time
280 \fB#include <tcl.h>\fR
282 \fBTcl_GetTime\fR(\fItimePtr\fR)
284 \fBTcl_SetTimeProc\fR(\fIgetProc, scaleProc, clientData\fR)
286 \fBTcl_QueryTimeProc\fR(\fIgetProcPtr, scaleProcPtr, clientDataPtr\fR)
288 .AS Tcl_GetTimeProc *getProc in
289 .AP Tcl_Time *timePtr out
290 Points to memory in which to store the date and time information.
291 .AP Tcl_GetTimeProc getProc in
292 Pointer to handler function replacing \fBTcl_GetTime\fR's access to the OS.
293 .AP Tcl_ScaleTimeProc scaleProc in
294 Pointer to handler function for the conversion of time delays in the
295 virtual domain to real-time.
296 .AP ClientData clientData in
297 Value passed through to the two handler functions.
298 .AP Tcl_GetTimeProc *getProcPtr out
299 Pointer to place the currently registered get handler function into.
300 .AP Tcl_ScaleTimeProc *scaleProcPtr out
301 Pointer to place the currently registered scale handler function into.
302 .AP ClientData *clientDataPtr out
303 Pointer to place the currently registered pass-through value into.
307 The \fBTcl_GetTime\fR function retrieves the current time as a
308 \fITcl_Time\fR structure in memory the caller provides. This
309 structure has the following definition:
312 typedef struct Tcl_Time {
318 On return, the \fIsec\fR member of the structure is filled in with the
319 number of seconds that have elapsed since the \fIepoch:\fR the epoch
320 is the point in time of 00:00 UTC, 1 January 1970. This number does
321 \fInot\fR count leap seconds \- an interval of one day advances it by
322 86400 seconds regardless of whether a leap second has been inserted.
324 The \fIusec\fR member of the structure is filled in with the number of
325 microseconds that have elapsed since the start of the second
326 designated by \fIsec\fR. The Tcl library makes every effort to keep
327 this number as precise as possible, subject to the limitations of the
328 computer system. On multiprocessor variants of Windows, this number
329 may be limited to the 10- or 20-ms granularity of the system clock.
330 (On single-processor Windows systems, the \fIusec\fR field is derived
331 from a performance counter and is highly precise.)
332 .SS "VIRTUALIZED TIME"
334 The \fBTcl_SetTimeProc\fR function registers two related handler functions
335 with the core. The first handler function is a replacement for
336 \fBTcl_GetTime\fR, or rather the OS access made by
337 \fBTcl_GetTime\fR. The other handler function is used by the Tcl
338 notifier to convert wait/block times from the virtual domain into real
341 The \fBTcl_QueryTimeProc\fR function returns the currently registered
342 handler functions. If no external handlers were set then this will
343 return the standard handlers accessing and processing the native time
344 of the OS. The arguments to the function are allowed to be NULL; and
345 any argument which is NULL is ignored and not set.
347 The signatures of the handler functions are as follows:
350 typedef void \fBTcl_GetTimeProc\fR(
351 Tcl_Time *\fItimebuf\fR,
352 ClientData \fIclientData\fR);
353 typedef void \fBTcl_ScaleTimeProc\fR(
354 Tcl_Time *\fItimebuf\fR,
355 ClientData \fIclientData\fR);
358 The \fItimebuf\fR fields contain the time to manipulate, and the
359 \fIclientData\fR fields contain a pointer supplied at the time the handler
360 functions were registered.
362 Any handler pair specified has to return data which is consistent between
363 them. In other words, setting one handler of the pair to something assuming a
364 10-times slowdown, and the other handler of the pair to something assuming a
365 two-times slowdown is wrong and not allowed.
367 The set handler functions are allowed to run the delivered time backwards,
368 however this should be avoided. We have to allow it as the native time can run
369 backwards as the user can fiddle with the system time one way or other. Note
370 that the insertion of the hooks will not change the behavior of the Tcl core
371 with regard to this situation, i.e. the existing behavior is retained.